Open Access. Powered by Scholars. Published by Universities.®

Engineering Science and Materials Commons™

Open Access. Powered by Scholars. Published by Universities.®

LSU Doctoral Dissertations

Discipline
Keyword
Publication Year

Articles 91 - 115 of 115

Full-Text Articles in Engineering Science and Materials

Aconitic Acid From Sugarcane: Production And Industrial Application, Nicolas Javier Gil Zapata Jan 2007

Aconitic Acid From Sugarcane: Production And Industrial Application, Nicolas Javier Gil Zapata

LSU Doctoral Dissertations

Trans aconitic acid (TAA) is the predominant organic acid in cane leaf matter (CLM) juice. Its concentration is three to six times higher than the level found in sugarcane stalks. The variation of composition in terms of total fermentable sugars (TFS), anions, and cations of the LCP85-384 sugarcane variety during 2003-2006 seasons, as well as the ripener (Polado-L®) effect were analyzed. TAA content ranged between 2.1-3.1 kg / t CLM. The TFS in CLM juice yielded a fermentation efficiency of 92%, four points lower than with sugar molasses. Liquid-liquid extraction (LLE), solid-liquid extraction and ion exchange were evaluated for the …

Go to article

Ultra-Violet Lithography Of Thick Photoresist For The Applications In Biomems And Micro Optics, Ren Yang Jan 2006

Ultra-Violet Lithography Of Thick Photoresist For The Applications In Biomems And Micro Optics, Ren Yang

LSU Doctoral Dissertations

UV lithography of thick photoresist is widely used in microelectromechanical systems (MEMS) and micro-optoelectromechanical systems (MOEMS). SU-8 is a typical negative tone thick photoresist for micro systems, and can be used for both structural material and pattern transfer. This dissertation presents an effort to comprehensively study these important subjects. The first part, and the most fundamental part of this dissertation concentrated on the numerical analysis and experimental study of the wavelength dependent absorbance of SU-8 and the diffraction effects on the sidewall profiles of the microstructures made using UV lithography of SU-8. This study has laid the foundation for all …

Go to article

Design And Fabrication Of Micro Transducers Using Cured Su-8 Polymer As Main Structural Material, Wen Dai Jan 2006

Design And Fabrication Of Micro Transducers Using Cured Su-8 Polymer As Main Structural Material, Wen Dai

LSU Doctoral Dissertations

Polymer based micro-transducers have many advantages over the traditional silicon based micro-transducers, such as easy integration with metal structures, design flexibility, and low fabrication costs. The characteristics of micro-transducers include converting electrical signals to/from mechanical response, the ability to sustain loading, sensitivity to external excitation, and etc. Some of the difficulties in realizing these characteristics include: characterizing material mechanical properties, techniques for producing electrically conductive polymer structures, and reliable fabrication procedures. In this dissertation, research addressing these difficulties is presented. The developed techniques are demonstrated in the design and fabrication of a SU-8 polymer based comb-drive micro-actuator. The micro-actuator used …

Go to article

A Micromechanical Approach For Predicting The Complex Shear Modulus And Accumulated Shear Strain Of Asphalt Mixtures From Binder And Mastics, Cristian Druta Jan 2006

A Micromechanical Approach For Predicting The Complex Shear Modulus And Accumulated Shear Strain Of Asphalt Mixtures From Binder And Mastics, Cristian Druta

LSU Doctoral Dissertations

Asphalt mixtures are particulate composite materials consisting of uniformly distributed mineral aggregates, asphalt binder and air voids. Mixtures of asphalt binder and filler, also called mastics, are often assumed to behave as simple viscoelastic materials, where the binders are stiffened by the filler. Because the workability and performance of bituminous mixes are known to be affected by the filler-asphalt mixture (or mastic) properties, this study is intended for performing rheological tests on asphalt binder and mastics and use the results in order to estimate performance parameters of asphalt mixture. The present work uses the PG64-22 asphalt binder test data initially …

Go to article

Loading And Recovery Behavior Of The Human Lumbar Spine Under Static Flexion, Guntulu Selen Hatipkarasulu Jan 2006

Loading And Recovery Behavior Of The Human Lumbar Spine Under Static Flexion, Guntulu Selen Hatipkarasulu

LSU Doctoral Dissertations

Musculoskeletal disorders account for 32 percent of work related injuries and illnesses. Extensive studies have been conducted to understand and explore the factors that affect the development of musculoskeletal disorders to provide effective control strategies. One of the most important factors that allow effective control strategies is the biomechanical factors. Among the biomechanical risk factors, exposures to repetitive static and vibratory activities are known to result in musculoskeletal disorders. A ligamento–muscular reflex activity exists in humans and animals to stabilize the knee, shoulder, elbow, ankle joints, and spine. This reflex activity decreases over time when static loading is applied, which …

Go to article

Towards A Generalized Team Task Complexity Model, Ashok Darisipudi Jan 2006

Towards A Generalized Team Task Complexity Model, Ashok Darisipudi

LSU Doctoral Dissertations

The objective of this research was to develop and validate a generalized team task-complexity model and framework by drawing on the literature from various team and task factors grouped into three task-dimensions, which compose task-complexity space and how these affect the task-performance. A number of task typologies have been presented in the teams' literature to better define and understand the critical role of the tasks and the associated team processes. In addition, most of the research work has defined team measures as highly abstract concepts not capable of providing the quantitative comparison of team performances from various domains. This research …

Go to article

A Project Improvement System For Effective Management Of Construction Projects, Shahriyar Mojahed Jan 2005

A Project Improvement System For Effective Management Of Construction Projects, Shahriyar Mojahed

LSU Doctoral Dissertations

The concept of construction productivity began in the early 20th century with a series of time and motion studies to improve bricklaying operations. A substantial number of subsequent studies focused on repetitive tasks and automation of the manufacturing operations and subsequently benefited manufacturing more than the construction industry. There has been a lack of studies for productivity improvement in the construction industry. Building upon the available body of knowledge as it related to productivity of manufacturing and construction industries, this study focused on developing a project improvement system for effective management of construction projects. Development of the system included a …

Go to article

Transport And Kinetics Of Aromatic Hydrocarbons Into Micron-Sized Liquid Droplets: With Applications To Atmospheric Chemistry, Suresh Raja Jan 2005

Transport And Kinetics Of Aromatic Hydrocarbons Into Micron-Sized Liquid Droplets: With Applications To Atmospheric Chemistry, Suresh Raja

LSU Doctoral Dissertations

In the natural process of wet deposition, gas-water interfaces play an important role in the transport of chemical contaminants in the atmosphere via fog, rain and cloud drops. Evidences from several other works point out deviations in gas-liquid partitioning as predicted by Henry’s law. Uptake and mass transfer of benzene, naphthalene, and phenanthrene was chosen to study in a falling droplet train apparatus. Higher droplet-to-vapor partition constant (KDV) was noted for diameters less than 200ìm and was attributed to surface adsorption and accumulation. Mass transfer of phenanthrene was dependent on gas-phase diffusion and mass accommodation at the interface, while the …

Go to article

Development Of High Performance Hybrid Syntactic Foams: Structure And Material Property Characterization, Rahul R. Maharsia Jan 2005

Development Of High Performance Hybrid Syntactic Foams: Structure And Material Property Characterization, Rahul R. Maharsia

LSU Doctoral Dissertations

Syntactic foams are light weight particulate composites that use hollow particles (microballoons) as reinforcement in a polymer resin matrix. High strength microballoons provide closed cell porosity which helps in reducing weight of the material. Due to their wide range of possible applications such as in aerospace and marine structures, it is desirable to modify the physical and mechanical properties of syntactic foams as per the requirements of an application. Various filler materials can be used to modify the foam microstructure to attain these desired properties. Compression tests have revealed that high density syntactic foams demonstrate poor damage tolerance and low …

Go to article

Supercritical Fluid Extraction Of Rice Bran With Adsorption On Rice Hull Ash, Paresh Manilal Patel Jan 2005

Supercritical Fluid Extraction Of Rice Bran With Adsorption On Rice Hull Ash, Paresh Manilal Patel

LSU Doctoral Dissertations

Rice bran oil was extracted using environmentally-friendly supercritical carbon dioxide at varying conditions. Experimental treatments included pressure (27.6, 41.4 and 55.2 MPa), temperature (40 and 60 oC) and flow rates (25, 45 and 65 g/min) of supercritical carbon dioxide. Extracts collected at different time intervals during 4-hour extraction runs in a 3-L extractor were analyzed for oil yield and antioxidants. Normal-phase HPLC was used for analyzing the extract for important antioxidant compounds of oryzanol, tocopherols, tocotrienols. Silica rich rice hull ash adsorbent was also incorporated in combined extraction-adsorption experiments under similar supercritical fluid conditions. Supercritical extraction yields of rice bran …

Go to article

Design And Fabrication Of Electromagnetic Micro-Relays Using The Uv-Liga Technique, John Dalton Williams Jan 2004

Design And Fabrication Of Electromagnetic Micro-Relays Using The Uv-Liga Technique, John Dalton Williams

LSU Doctoral Dissertations

This dissertation reports a research effort to microfabricate an electromagnetic relay for power applications using a multilayer UV-LIGA process. A mechanically wrapped coil was used and very simple design for the magnetic circuit was adopted to increase the design flexibility and performances. The broad material selection and the capability of making high aspect ratio microstructures of the UV-LIGA make the technology best suited for fabricating microelectromechanical power relays. Fabrication of the device required significant advances in the optical lithography of SU-8 negative photoresist. Research proved that aspect-ratios up to 40:1 in isolated open field structures of thickness between 1 and …

Go to article

Processing, Microstructure And Mechanical Behavior Of Nanocomposite Multilayers, Zuqiang Qi Jan 2004

Processing, Microstructure And Mechanical Behavior Of Nanocomposite Multilayers, Zuqiang Qi

LSU Doctoral Dissertations

Nanoscale multilayer coatings have high potential for numerous engineering applications because they can exhibit enhanced properties due to nanoscale effects and combine different properties from individual components. At present, scale effects on the mechanical behavior of multilayers are not well understood. Three multilayer nanocomposite systems, namely Al/Al2O3, Ti/TiN, and Cr/a-C, have been synthesized by using a dual-gun e-beam physical vapor deposition, to investigate the effect of layer thickness, the nature of components and their microstructures on the mechanical behavior. The deposited Al and Ti nanolayers were found to have polycrystalline fcc and hcp structure, respectively, the Cr and TiN layers …

Go to article

Synthesis, Structure, And Tribological Behavior Of Nanocomposite Dlc Based Thin Films, Varshni Singh Jan 2004

Synthesis, Structure, And Tribological Behavior Of Nanocomposite Dlc Based Thin Films, Varshni Singh

LSU Doctoral Dissertations

Diamond-like carbon (DLC) films possess a combination of attractive properties and have been largely employed to modify the tribological behavior of materials. Nanocomposite, metal-containing DLC films are the new generation of these coatings providing tremendous potential to modify and tailor their properties expanding their applications in the field of nanotechnology. The present study investigates nanoscale effects on the tribological behavior of composite nanostructured DLC-based films and functional coatings. Three aspects were studied: (i) effect of Cr interlayer on a functionally gradient substrate; (ii) nanoparticulate Cr-containing DLC (Cr-DLC) films; and (iii) nanocomposite multilayered Cr/DLC coatings. Intensified plasma assisted nitriding produced a …

Go to article

Multifunctional Nanocomposite Co-Containing Diamondlike Carbon Thin Films, Fengli Wang Jan 2004

Multifunctional Nanocomposite Co-Containing Diamondlike Carbon Thin Films, Fengli Wang

LSU Doctoral Dissertations

Metal-containing, hydrogenated carbon films (Me-a-C:H) is a special class of nanocomposite films of particular interest since they can be multifunctional through the synergistic interaction of their individual components. Thus, nanocomposite thin films possess high potential in a wide field of engineering applications, especially in small scale devices. A series of multifunctional nanocomposite Co-a-C:H thin films have been synthesized by a hybrid chemical vapor deposition (CVD) and physical vapor deposition (PVD) process to uncover the relationship between synthesis, microstructure and properties. The effects of deposition parameters on the microstructural evolution and properties have been systematically studied. The results showed that the …

Go to article

Morphological Evolution And Instabilities Of Solid Thin Films And Wires, Wanxi Kan Jan 2004

Morphological Evolution And Instabilities Of Solid Thin Films And Wires, Wanxi Kan

LSU Doctoral Dissertations

This dissertation can be divided into four parts. In part I (Chapter 2), the diffusion controlled growth of multiple compound phases is studied with the nonlinear Kirkendall effect included. This part analyzes the growth of N compound phases. The method of finding intrinsic diffusion coefficients from only the positions of interfaces is found for two layers. In addition, the asymptotic analysis valid for small concentration gradients is applied to the “multi-foil” method of measuring intrinsic diffusion coefficients and yields an analytic solution for the displacement curve. A bounded solid film on a substrate can breakup from the edge into islands …

Go to article

Modeling The Effects Of Rainfall Intensity And Deep Chiseling On Infiltration And Runoff Within Drainmod For Alluvial Soils, Daniel Nyabiba Moriasi Jan 2004

Modeling The Effects Of Rainfall Intensity And Deep Chiseling On Infiltration And Runoff Within Drainmod For Alluvial Soils, Daniel Nyabiba Moriasi

LSU Doctoral Dissertations

Accurate hydrologic models are needed to aid engineers and researchers design, install and evaluate efficient and cost-effective agricultural water management systems to reduce risks associated with food production, and to reduce soil erosion and water pollution. One model used for the alluvial soils of Louisiana is DRAINMOD. This model does not accurately predict infiltration and runoff for the crusting-prone alluvial soils of Louisiana. The main goal of this study was to modify the current DRAINMOD model to incorporate the effects of rainfall intensity and deep chiseling to improve its estimation of infiltration and surface runoff. The second goal was to …

Go to article

Optimization Of A Skewed Logistic Distribution With Respect To The Kolmogorov-Smirnov Test, James Charles Finney Jan 2004

Optimization Of A Skewed Logistic Distribution With Respect To The Kolmogorov-Smirnov Test, James Charles Finney

LSU Doctoral Dissertations

The four-parameter kappa distribution (Hosking 1994) was analyzed with respect to the various possible shapes of the probability density function. The general form for the cumulative distribution function when both h and k are non-zero is: F(x) = { 1 - h [ 1 - k ( x - ξ ) / α ]1/k }1/h. The parameters h and k work together to define the function's shape, ξ affects location, and α is the scale parameter. A method of selecting parameters to minimize the Kolmogorov-Smirnov test statistic, D, was developed. The technique was first described for the …

Go to article

Rotary Kiln Incineration Of Hazardous Wastes: Pilot-Scale Studies At Louisiana State University, John Sutherland Earle Jan 2003

Rotary Kiln Incineration Of Hazardous Wastes: Pilot-Scale Studies At Louisiana State University, John Sutherland Earle

LSU Doctoral Dissertations

Studies of incineration of surrogates for hazardous wastes are conducted in the pilot-scale rotary kiln incinerator (RKI) at Louisiana State University (LSU) in Baton Rouge, Louisiana. The purpose of the research is to investigate methods of treating and destroying hazardous wastes in a cost-effective and environmentally sound way. The objective is to provide process data that will contribute to increased knowledge for RKI design and operation. The LSU facility is a College of Engineering Combustion Laboratory that is unique in its large size as a university laboratory. It is equipped with individual instruments for analysis of O2, CO, …

Go to article

Optimization And Automation Of A Thermal Oyster Shucking Process, Daniel Edgar Martin Jan 2003

Optimization And Automation Of A Thermal Oyster Shucking Process, Daniel Edgar Martin

LSU Doctoral Dissertations

Louisiana Gulf Coast oysters (Crassostrea virginica) were subjected to thermal shucking treatments to effect adductor muscle release from both left and right valves. The oysters were instrumented with thermocouples to monitor and record process temperatures in the oysters and on the shell. Following treatment, the oysters were evaluated for relaxation and release of the adductor muscle, meat quality and texture, and for the effect of the treatments on the storage life of the oysters as measured by total microbial plate counts. The treatments of many oysters resulted in a complete release of the adductor muscle from the shell while maintaining …

Go to article

Finite-Horizon Operations Planning For A Lean Supply Chain System, Ahmad Diponegoro Jan 2003

Finite-Horizon Operations Planning For A Lean Supply Chain System, Ahmad Diponegoro

LSU Doctoral Dissertations

This dissertation studies an operational policy for a lean supply chain system consisting of a manufacturer, multiple suppliers and multiple buyers. The manufacturer procures raw materials from the suppliers and converts them into finished products, which are then shipped in batches to the buyers at certain intervals of times. Three distinct but inseparable problems are addressed: single supplier and single buyer with fixed delivery size (FD), multiple suppliers and multiple buyers with individual delivery schedule (MD), and time dependent delivery quantity with trend demand (TD). The mathematical formulations of these supply systems are categorized as mixed-integer, nonlinear programming problems (MINLAP) …

Go to article

Progressive Fatigue Effects On Manual Lifting Factors, Anthony D'Wayne Banks Jan 2003

Progressive Fatigue Effects On Manual Lifting Factors, Anthony D'Wayne Banks

LSU Doctoral Dissertations

Much evidence suggests that the cause of lower back pain (LBP) and injury is frequently related to the posture of lifting, the load, muscle fatigue, and other factors. The purpose of this study was to evaluate the effect of progressive fatigue on factors that have previously been associated with increased risk of LBP in various occupational settings, during a repetitive lifting task where freestyle lifting technique was utilized. A laboratory experiment was conducted to evaluate several fatigue analysis, electromyography amplitude, kinematic, and kinetic parameters of repetitive freestyle lifting during a 2-hour lifting period. Each of ten (10) young adult male …

Go to article

Characterization Of Syntactic Foams And Their Sandwich Composites: Modeling And Experimental Approaches, Nikhil Gupta Jan 2003

Characterization Of Syntactic Foams And Their Sandwich Composites: Modeling And Experimental Approaches, Nikhil Gupta

LSU Doctoral Dissertations

Hollow particle filled polymers known as syntactic foams are lightweight and highly damage tolerant. Syntactic foams are used as core materials in sandwich composites. The use of such materials in aeronautical and space structures make it necessary to understand their characteristics for various environmental and loading conditions. The first part of the present work takes modeling and finite element analysis approach to understand and predict the deformation behavior of syntactic foams. Contact analysis is performed on single particle models by the finite element analysis approach. In the second part extensive experiments are carried out to characterize syntactic foams for hygrothermal …

Go to article

Block-Level Discrete Cosine Transform Coefficients For Autonomic Face Recognition, Willie L. Scott, Ii Jan 2003

Block-Level Discrete Cosine Transform Coefficients For Autonomic Face Recognition, Willie L. Scott, Ii

LSU Doctoral Dissertations

This dissertation presents a novel method of autonomic face recognition based on the recently proposed biologically plausible network of networks (NoN) model of information processing. The NoN model is based on locally parallel and globally coordinated transformations. In the NoN architecture, the neurons or computational units form distributed networks, which themselves link to form larger networks. In the general case, an n-level hierarchy of nested distributed networks is constructed. This models the structures in the cerebral cortex described by Mountcastle and the architecture based on that proposed for information processing by Sutton. In the implementation proposed in the dissertation, the …

Go to article

Data Mining And Knowledge Discovery: A Guided Approach Base On Monotone Boolean Functions, Vetle Ingvald Torvik Jan 2002

Data Mining And Knowledge Discovery: A Guided Approach Base On Monotone Boolean Functions, Vetle Ingvald Torvik

LSU Doctoral Dissertations

This dissertation deals with an important problem in Data Mining and Knowledge Discovery (DM & KD), and Information Technology (IT) in general. It addresses the problem of efficiently learning monotone Boolean functions via membership queries to oracles. The monotone Boolean function can be thought of as a phenomenon, such as breast cancer or a computer crash, together with a set of predictor variables. The oracle can be thought of as an entity that knows the underlying monotone Boolean function, and provides a Boolean response to each query. In practice, it may take the shape of a human expert, or it …

Go to article

Impact Of Subject Related Factors And Position Of Flight Control Stick On Acquisition Of Simulated Flying Skills Using A Flight Simulator, Bo-Keun Cho Jan 2002

Impact Of Subject Related Factors And Position Of Flight Control Stick On Acquisition Of Simulated Flying Skills Using A Flight Simulator, Bo-Keun Cho

LSU Doctoral Dissertations

Increasing demand on aviation industry calls for more pilots. Thus, pilot training systems and pilot-candidate screening systems are essential for civil and military flying training institutes. Before actual flight training, it is not easy to determine whether a flight trainee will be successful in the training. Due to the high cost of actual flight training, it would be better if there were low cost methods for screening and training candidates prior to the actual flight training. This study intended to determine if subject related factors and flight control stick position have an impact on acquisition of simulated flying skills using …

Go to article

First Prev